Help with Jandy LXI400N heater.

[Riker0007]

So, I had to replace my gas line as it was leaking and I found out the previous plumber did not wrap the pipe and it rusted and they failed to tighten enough one pipe that was under concrete. After everything was tested and good, I tried to fire up the heater (jandy lxi400n) and the blower turns on, I hear the gas valve ( I think) click on and then a poof and it heats what gas is in there but never turns on. At the gas meter I can hear the gas being drawn but only for a sec or two. I took apart the igniter and it looks fine and tested about 58 ohms. The flames sensor looks fine too. I'm not sure what is the issue? Gas valve or Fenwal ignition unit?
I hate to buy parts only for it to be something else. Any help would be great.
THanks in advance.
Don

[Denniswiseman]

Did you purge the air out of the new gas line

[Riker0007]

Hi,
Yes purged the line.
I replaced the fynwal ignitor, the electronics board and still was having the issue, so I replaced the gas valve. It worked and I thought that was it. NOPE, tested a couple of days after it seemed to work on and off a few times; Back to doing the same thing. I can hear the gas at the main go for a sec or two but stops. At the heater I can hear it click and then a big poof and it heats I can feel heat for a sec or two and then nothing. What else could it be or just toss in the damn towel and buy a new one.
Please help.

[Denniswiseman]

You could get a service engineer to look at it
Would probably have ben cheaper in the long run